So, here's the lesson that I learned when I was about 23 years old.
At the time, I had a CIS degree and had been programming for about 5 years, mostly Java, Perl and PHP (early 2000s).
I knew PHP really well. Used it professionally, used it in my hobbies. There was something I was trying to figure out how to do and I couldn't find a clear answer for it online anywhere so I finally ended up buying a book that had references too it. Big 600 page Wrox book I think.
Well, I opened up the book and found the answer I was looking for. Then I noticed something on the next page that I didn't realize you could do and would have made my life soooo much easier if I'd known about it earlier.
After that I sat down and read the book cover to cover despite having been working with PHP for 5 years at that point and I learned so much. Really leveled me up.
Now, anytime I want to learn anything I go straight for a book so that I can get a comprehensive picture of all of the available tools and how they work together, from an expert. Makes everything afterwards a lot easier.